Transmission Line Conductor Selection: ACSR, AAAC, ACSS, ACCC, HTLS – Technical Comparison

An in-depth engineering reference on conductor types, mechanical properties, thermal limits, sag-tension behavior, corona performance, and cost-effectiveness for modern transmission line design.

1. Introduction

Conductor selection affects electrical performance, mechanical loading, sag, thermal rating, reliability, and project cost. This guide compares ACSR, AAAC, ACCC, ACSS, and HTLS conductors using engineering criteria.

2. Key Electrical Parameters

• Ampacity
• Corona onset voltage
• Radio interference voltage (RIV)
• Skin effect
• AC resistance

3. Mechanical Parameters

• Ultimate tensile strength
• Modulus of elasticity
• Creep
• Wind and ice loads

4. Conductor Types

4.1 ACSR (Aluminum Conductor Steel Reinforced)

The most widely used conductor due to high tensile strength and cost-effectiveness.

4.2 AAAC (All Aluminum Alloy Conductor)

Corrosion-resistant, lighter, higher conductivity.

4.3 ACSS (Aluminum Conductor Steel Supported)

Designed for high-temp operation up to 200°C.

4.4 ACCC (Advanced Composite Core Conductor)

Hybrid carbon/glass core with low sag and high current rating.

4.5 HTLS Conductors

High Temperature Low Sag technology for uprating existing lines.

5. Sag–Tension Performance Comparison

Type	Sag @ 25°C	Sag @ 75°C	Rating
ACSR Drake	11.9 m	15.8 m	Good
ACSS Drake	12.1 m	13.5 m	Very Good
ACCC Drake	9.1 m	9.9 m	Excellent

6. Corona Performance

ACCC and AAAC offer superior corona behavior due to smoother surfaces.

7. Cost & Lifecycle Analysis

• ACSR – lowest cost
• AAAC – moderate
• ACSS – moderate
• ACCC – highest initial cost but best performance

8. Sample Calculation (ACSR Drake, 450 m Span)

Using parabolic sag approximation:

s = wL² / (8H)

9. Best Practices

• Match conductor type with terrain and rating requirements
• Use HTLS for uprating existing corridors
• Use ACCC in long spans or harsh terrain
• Use AAAC in corrosive/coastal regions